Rotating fluid machine

ABSTRACT

A rotary valve of a rotating fluid machine is constructed by bringing into contact, on sliding faces which are orthogonal to an axis, a moving valve plate provided on a rotor and a stationary valve plate provided on a valve body. An annular member pivotably supports the valve body by a fulcrum shaft. The annular member has a pair of projections at its two ends. The pair of projections are engaged slidably in the direction of the axis with a pair of guide grooves formed in a rear cover. When the valve body is pressed in the direction of the axis to bring the sliding faces into close contact with each other, the pair of projections receive a uniform frictional resistance from the guide grooves, so that the annular member is prevented from inclining off a plane orthogonal to the axis. Therefore, the compliance of the sliding faces can be secured to prevent a working medium from leaking and to suppress uneven wear of the sliding faces.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotating fluid machineprovided with a casing, a rotor rotatably supported by the casing, aworking section provided on the rotor, and a rotary valve, providedbetween the casing and the rotor, for controlling the supply anddischarge of the working medium to and from the working section.

[0003] 2. Description of the Related Art

[0004] In a rotary valve for rotating fluid machines of this kind, amoving valve plate provided on the rotor and a stationary valve plateprovided on a valve body engaged with the casing to be unable to rotateand movable in the direction of the axis of the rotor are brought intocontact with each other on sliding faces orthogonal to the axis, and therotation of the moving valve plate relative to the stationary valveplate causes steam of high temperature and high pressure to besuccessively supplied to or discharged from a group of axial pistoncylinders provided on the rotor. In that process, it is necessary topermit the valve body to move in the direction of the axis and securethe compliance of the sliding faces, while preventing the frictionalforce acting on the sliding faces between the moving valve platerotating together with the rotor and the stationary valve plate fromcausing the valve body integrated with the stationary valve plate to bedragged by and accompany the rotor in the rotation.

[0005] In view of this problem, a rotating fluid machine described inJapanese Patent Laid-Open No. 2002-256805 has a pin planted in oneposition on the outer circumference of the valve body in the radialdirection and engaged with a notch formed in the inner circumferentialface of the casing in the direction of the axis.

[0006] The valve body accommodated in a concave in the casing via asealing member secures the compliance of the sliding faces between themoving valve plate and the stationary valve plate while oscillatingaround the axis within the compression margin of the sealing member.However, in the conventional device, as the valve body is engaged withthe casing in only one position on the outer circumferential face wherethe pin is planted, the valve body cannot smoothly oscillate around theaxis, and the oscillation of the valve body around the pin in a positionoff the axis may not only deteriorate the compliance of the slidingfaces but also cause uneven wear of the sliding faces.

[0007] In view of the problems noted above, the present invention has anobject to increase the compliance of the sliding faces of the rotaryvalve of the rotating fluid machine, thereby preventing the workingmedium from leaking.

SUMMARY OF THE INVENTION

[0008] In order to achieve the object stated above, according to a firstfeature of the present invention, there is proposed a rotating fluidmachine comprising: a casing; a rotor rotatably supported by the casing;a working section disposed on the rotor; and a rotary valve, providedbetween the casing and the rotor, for controlling the supply anddischarge of a working medium to and from the working section, therotary valve being constructed by bringing into contact, on slidingfaces which are orthogonal to an axis of the rotor, a moving valve plateprovided on the rotor and a stationary valve plate provided on a valvebody engaged with the casing to be unable to rotate and movable in thedirection of the axis, wherein two projections are provided in a firstradial direction at two ends of an annular member loosely fitted ontothe outer circumference of the valve body, and engaged slidably in thedirection of the axis with guide grooves formed in the casing, andwherein the valve body is pivotably supported on the annular member viaa fulcrum shaft arranged in a second radial direction orthogonal to thefirst radial direction.

[0009] With the configuration described above, two projections areprovided in a first radial direction at two ends of an annular memberloosely fitted onto the outer circumference of the valve body, andengaged slidably in the direction of the axis with guide grooves formedin the casing. Thus, when the valve body is biased in the axialdirection so that the sliding faces of the stationary valve plate andthe moving valve pate are brought into close contact with each other,the two projections receive a uniform frictional resistance, and theannular member is thereby prevented from inclining off the planeorthogonal to the axis. Even if the annular member is inclined due tothe difference in frictional resistance which the two projectionsreceives from the guide grooves, as the valve body is pivotablysupported on the annular member via the fulcrum shaft arranged in thesecond radial direction, the valve body can be reliably prevented frominclining off the axis L, and the compliance of the sliding faces can besecured, thereby preventing the working medium from leaking andsuppressing uneven wear of the sliding faces.

[0010] Further, according to a second feature of the present invention,in addition to the first feature, the two projections of the annularmember can slide with respect to the guide grooves of the casing in thefirst radial direction, and the valve body can slide along the fulcrumshaft in the second radial direction.

[0011] With the configuration described above, the operation of theOldham's coupling constructed of the annular member and the fulcrumshaft enables the valve body to freely move relative to the casingwithin the plane orthogonal to the axis. Therefore, even if the valvebody becomes inclined off the axis, the free movement of the valve bodywithin the plane orthogonal to the axis prevents wrenching fromoccurring between the valve body and the casing, thereby securing thecompliance of the sliding faces.

[0012] A group of axial piston cylinders 56 in preferred embodimentscorrespond to the working section according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a vertical sectional view of an expander according to afirst preferred embodiment.

[0014]FIG. 2 is a sectional view taken on line 2-2 in FIG. 1.

[0015]FIG. 3 is a view taken on line 3-3 in FIG. 1.

[0016]FIG. 4 is an enlarged view of Part 4 in FIG. 1.

[0017]FIG. 5 is an enlarged view of Part 5 in FIG. 1.

[0018]FIG. 6 is an exploded perspective view of a rotor.

[0019]FIG. 7 is a sectional view taken on line 7-7 in FIG. 4.

[0020]FIG. 8 is a sectional view taken on line 8-8 in FIG. 4.

[0021]FIG. 9 is an enlarged view of Part 9 in FIG. 4.

[0022]FIG. 10 is a sectional view taken on line 10-10 in FIG. 5.

[0023]FIG. 11 is a sectional view taken on line 11-11 in FIG. 5.

[0024]FIG. 12 is a sectional view taken on line 12-12 in FIG. 5.

[0025]FIG. 13 is a sectional view taken on line 13-13 in FIG. 5.

[0026]FIG. 14 is a view in arrowed direction 14 in FIG. 13.

[0027]FIG. 15 is a view in arrowed direction 15 in FIG. 13.

[0028]FIG. 16 is an exploded perspective view of an Oldham's coupling.

[0029]FIG. 17 is an exploded perspective view of an Oldham's coupling ina second preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the present invention will be describedbelow with reference to the accompanying drawings.

[0031] As shown in FIG. 1 through FIG. 9, an expander E according to afirst embodiment is used in, for example, a Rankine cycle system. Itconverts thermal energy and pressure energy of high-temperaturehigh-pressure steam as a working medium into mechanical energy andsupplies the converted energy. The casing 11 of the expander E isprovided with a casing body 12, a front cover 15 connected to the frontopening of the casing body 12 with a plurality of bolts 14 . . . with asealing member 13 therebetween, a rear cover 18 fitted to the rearopening of the casing body 12 with a plurality of bolts 17 . . . with asealing member 16 therebetween, and an oil pan 21 fitted to the bottomopening of the casing body 12 with a plurality of bolts 20 . . . with asealing member 19 therebetween.

[0032] A rotor 22 is arranged to be rotatable around an axis L extendingin the middle of the casing 11 in the back and forth directions, andsupported in front by combined angular bearings 23 f and 23 r disposedon the front cover 15 and on the back by a radial bearing 24 disposed onthe casing body 12. A swash plate holder 28 is integrally formed on therear face of the front cover 15. A swash plate 31 is rotatably supportedby this swash plate holder 28 via an angular bearing 30. The axis of theswash plate 31 is inclined relative to the axis L of the rotor 22 at afixed angle.

[0033] The rotor 22 is provided with an output shaft 32 supported on thefront cover 15 with the combined angular bearings 23 f and 23 r, threesleeve supporting flanges 33, 34 and 35 formed integrally with oneanother on the rear part of the output shaft 32 via notches 57 and 58 ofa predetermined width (see FIG. 4 and FIG. 9), a rotor head 38 connectedto the rear sleeve supporting flange 35 with a plurality of bolts 37 . .. via a metal gasket 36 integrally and supported on the casing body 12by the radial bearing 24, and a thermally insulating cover 40 fittedonto the three sleeve supporting flanges 33, 34 and 35 from front andconnected with a plurality of bolts 39 . . . to the front sleevesupporting flange 33.

[0034] Five sleeve supporting holes 33 a . . . , 34 a . . . and 35 a . .. are respectively bored in the three sleeve supporting flanges 33, 34and 35 around the axis L at 72° intervals. Five cylinder sleeves 41 . .. are fitted into the respective sleeve supporting holes 33 a . . . , 34a . . . and 35 a . . . from behind. Formed at the rear end of each ofthe cylinder sleeves 41 is a flange 41 a, which is positioned in theaxial direction in contact with the metal gasket 36 in a state in whichit is fitted onto a stepped portion 35 b formed in the sleeve supportinghole 35 a of the rear sleeve supporting flange 35 (see FIG. 9). A piston42 is slidably fitted within each of the cylinder sleeves 41, the frontend of the piston 42 is in contact with a dimple 31 a formed in theswash plate 31, and a steam expansion chamber 43 is partitioned betweenthe rear end of the piston 42 and the rotor head 38.

[0035] A plate-shaped bearing holder 92 is laid over the front face ofthe front cover 15 with a sealing member 91 therebetween and fixed withbolts 93 . . . . A pump body 95 is laid over the front face of thebearing holder 92 with a sealing member 94 therebetween and fixed withbolts 96 . . . . The combined angular bearings 23 f and 23 r arepositioned between the stepped portion of the front cover 15 and thebearing holder 92, and fixed in the direction of the axis L.

[0036] A shim 97 of a predetermined thickness is placed between a flange32 d formed in the output shaft 32 supporting the combined angularbearings 23 f and 23 r and the inner races of the combined angularbearings 23 f and 23 r. The inner races of the combined angular bearings23 f and 23 r are fastened with nuts 98 screwed onto the outercircumference of the output shaft 32. As a result, the output shaft 32is positioned in the direction of the axis L relative to the combinedangular bearings 23 f and 23 r, namely with respect to the casing 11.

[0037] The combined angular bearings 23 f and 23 r are attached inmutually reverse orientations, and support the output shaft 32 not onlyin the radial direction but also immovably in the direction of the axisL. Thus, one combined angular bearing 23 f is arranged to restrict theforward movement of the output shaft 32, while the other combinedangular bearing 23 r is arranged to restrict the backward movement ofthe output shaft 32.

[0038] As the combined angular bearings 23 f and 23 r are used as abearing for the front part of the rotor 22, one of the loads arisingtoward the opposite ends of the axis L in the expansion chambers 43 . .. in a predetermined operating state of the expander E is transmittedvia the rotor 22 to the inner races of the combined angular bearings 23f and 23 r, and the other load is transmitted via the swash plate 31 andthe swash plate holder 28 of the front cover 15 to the outer races ofthe combined angular bearings 23 f and 23 r. These two loads compressthe swash plate holder 28 of the front cover 15 held between the angularbearing 30 supporting the swash plate 31 and the combined angularbearings 23 f and 23 r supporting the rotor 22, resulting in an enhancedrigidity of the mechanism. Moreover, the integral configuration of theswash plate holder 28 with the front cover 15 as in this embodiment ofthe invention makes the structure more rigid and simpler.

[0039] Further, by incorporating the angular bearing 30 supporting theswash plate 31 and the combined angular bearings 23 f and 23 rsupporting the rotor 22 into the front cover 15, it is possible toaccomplish the assembling process in the units of “the rotor 22 and thepiston 42 . . . ”, “assembly of the front cover 15” and “the pump body95” thereby improving the efficiency of procedures such as rearrangementof the piston 42 . . . and the replacement of an oil pump 49.

[0040] The radial bearing 24 supporting the rotor head 38 whichconstitutes the rear end of the rotor 22 is an ordinary ball bearingsupporting only the load in the radial direction. To enable the rotorhead 38 to slide in the direction of the axis L relative to the radialbearing 24, a gap a is formed between the rotor head 38 and the innerrace of the radial bearing 24 (see FIG. 5).

[0041] An oil passage 32 a extending on the axis L is formed within theoutput shaft 32 integral with the rotor 22. The front end of the oilpassage 32 a branches in radial directions to communicate with anannular groove 32 b on the outer circumference of the output shaft 32.In a radially inner position of the sleeve supporting flange 34 at thecenter of the rotor 22, an oil passage blocking member 45 is screwedinto the inner circumference of the oil passage 32 a with a sealingmember 44 therebetween. A plurality of oil holes 32 c . . . extend fromthe nearby oil passage 32 a outward in the radial direction, and open inthe outer circumferential face of the output shaft 32.

[0042] A trochoidal oil pump 49 is arranged between a concave 95 aformed in the front face of the pump body 95 and a pump cover 48 fixedwith a plurality of bolts 47 . . . to the front face of the pump body 95with a sealing member 46 therebetween, and includes an outer rotor 50rotatably fitted into the concave 95 a, and an inner rotor 51 fixed tothe outer circumference of the output shaft 32 to engage with the outerrotor 50. The inner space of the oil pan 21 communicates with the intakeport 53 of the oil pump 49 via an oil pipe 52 and the oil passage 95 bof the pump body 95. The discharge port 54 of the oil pump 49communicates with the annular groove 32 b of the output shaft 32 via theoil passage 95 c of the pump body 95.

[0043] The piston 42 slidably fitted into the cylinder sleeve 41consists of an end portion 61, a middle portion 62 and a top portion 63.The end portion 61 is a member having a spherical portion 61 a incontact with the dimple 31 a of the swash plate 31, and is welded ontothe tip of the middle portion 62. The middle portion 62 is a cylindricalmember having a large-capacity hollow space 62 a, and has in the outercircumferential part near the top portion 63 a smaller diameter part 62b slightly reduced in diameter. A plurality of oil holes 62 c . . . areformed to penetrate the smaller diameter part 62 b in the radialdirection. A plurality of spiral oil grooves 62 d . . . are formed inthe outer circumferential part ahead of the smaller diameter part 62 b.The top portion 63 facing the expansion chambers 43 is formed integrallywith the middle portion 62. A thermally insulating space 65 (see FIG. 9)is formed between a partition wall 63 a formed inside the space and alid member 64 fitted and welded onto its rear end face. Fitted to theouter circumference of the top portion 63 are two compression rings 66and one oil ring 67. An oil ring groove 63 b into which the oil ring 67is fitted, communicates via a plurality of oil holes 63 c . . . with thehollow space 62 a of the middle portion 62.

[0044] The end portion 61 and the middle portion 62 of the piston 42 arebuilt of high carbon steel, and the top portion 63, of stainless steel.The end portion 61 undergoes induction quenching, and the middle portion62, plain quenching. As a result, the piston 42 obtains a high surfacestress resistance in the end portion 61 which is in contact with theswash plate 31 under a high surface stress, a wear resistance in themiddle portion 62 which is in sliding contact with the cylinder sleeves41 under poor lubricating conditions, and a heat and corrosionresistance in the top portion 63 which faces the expansion chambers 43to be exposed to high temperature and high pressure.

[0045] An annual groove 41 b (see FIG. 6 and FIG. 9) is formed in theouter circumference of the middle portion of each cylinder sleeve 41,and a plurality of oil holes 41 c . . . are formed in this annual groove41 b. Irrespective of the mounting position of the cylinder sleeve 41 inthe rotating direction, the oil holes 32 c . . . formed in the outputshaft 32 and oil holes 34 b . . . (see FIG. 4 and FIG. 6) formed in themiddle sleeve supporting flange 34 of the rotor 22 communicate with theannual groove 41 b. A space 68 formed between the thermally insulatingcover 40 and the sleeve supporting flanges 33 and 35 respectively beforeand behind the rotor 22 communicates with the inner space of the casing11 via oil holes 40 a . . . (see FIG. 4 and FIG. 7) formed in thethermally insulating cover 40.

[0046] An annular lid member 69 is welded onto the front side of therotor head 38 connected with the bolts 37 . . . to the rear face of thesleeve supporting flange 33 in the front side of the rotor 22, or ontothe expansion chambers 43 . . . . An annular thermally insulating space70 (see FIG. 9) is defined on the back or rear face of the lid member69. The rotor head 38 is positioned in the rotating direction by a knockpin 55 relative to the rear sleeve supporting flange 35.

[0047] The five cylinder sleeves 41 . . . and the five pistons 42 . . .constitute a group of axial piston cylinders 56 according to the presentinvention.

[0048] Next will be described with reference to FIG. 5 and FIG. 10through FIG. 15 the structure of a rotary valve 71 for supplying anddischarging steam to and from the five expansion chambers 43 . . . ofthe rotor 22.

[0049] As shown in FIG. 5, the rotary valve 71 arranged along the axis Lof the rotor 22 is provided with a valve body 72, a cap member 102fitted onto the rear outer circumference of the valve body 72 with asealing member 101 therebetween, an annular member 104 loosely fittedonto the middle outer circumference of the valve body 72 andoscillatably supported by a fulcrum shaft 103, a stationary valve plate73, and a moving valve plate 74. The moving valve plate 74, in a stateof being positioned by a knock pin 75 in the rotating direction on therear side of the rotor 22, is fixed with bolts 76 screwed onto the oilpassage blocking member 45 (see FIG. 4). The bolts 76 also have afunction to fix the rotor head 38 to the output shaft 32.

[0050] As is clear from FIG. 5 when referenced together with FIG. 13through FIG. 16, the annular member 104 includes, at the opposite endsof a first radial direction X-X, a pair of projections 104 a and 104 b.Those projections 104 a and 104 b have a rectangular section with itscorners rounded, and are engaged with a pair of guide grooves 18 c and18 c formed in the rear cover 18, in the direction of the axis L, to beslidable in the direction of the axis L and in the radial direction(first radial direction X-X). The fulcrum shaft 103 pressed into twothrough holes 104 c and 104 c formed in the annular member 104 isarranged in a second radial direction Y-Y orthogonal to the first radialdirection X-X. The fulcrum shaft 103 loosely penetrates the valve body72, and therefore the valve body 72 can slide relative to the annularmember 104 in the second radial direction Y-Y and oscillate relative tothe annular member 104 around the fulcrum shaft 103.

[0051] In other words, since the engagement of the projections 104 a and104 b with the guide grooves 18 c and 18 c enables the annular member104 to move relative to the rear cover 18 in the first radial directionX-X, and the valve body 72 is guided by the fulcrum shaft 103 toreliably move in relative terms in the second radial direction Y-Y, thevalve body 72 can freely move relative to the rear cover 18 in the planeorthogonal to the axis L. Therefore, the annular member 104 and thefulcrum shaft 103, while restricting the rotation of the valve body 72relative to the rear cover 18, constitute an Oldham's coupling whichpermits axial misalignment between the rear cover 18 and the valve body72.

[0052] Referring again to FIG. 5, the stationary valve plate 73 incontact with the moving valve plate 74 via the flat sliding faces 77 isfixed to the center of the front face of the valve body 72 with a singlebolt 78, and fixed to the outer circumference of the valve body 72 withan annular fixed ring 79 and a plurality of bolts 80. When it is fixed,a stepped portion 79 a formed on the inner circumference of the fixedring 79 is pressed onto the outer circumference of the stationary valveplate 73 in a spigot-fit manner, and a stepped portion 79 b formed onthe outer circumference of the fixed ring 79 is spigot-fitted onto theouter circumference of the valve body 72, thereby ensuring a coaxialrelationship of the stationary valve plate 73 to the valve body 72.Further, a knock pin 81 for positioning the stationary valve plate 73 inthe rotational direction is arranged between the valve body 72 and thestationary valve plate 73.

[0053] Therefore, as the rotor 22 turns, the moving valve plate 74 andthe stationary valve plate 73 turn relative to each other in closecontact with each other on the sliding faces 77. The stationary valveplate 73 and the moving valve plate 74 are made of a highly durablematerial, such as carbon or ceramic, and their durability can be furtherenhanced by affixing a member having excellent heat resistance,lubricating performance, corrosion resistance and wear resistance to thesliding faces 77, or by coating them with such a material.

[0054] The cap member 102 fitted onto the outer circumference of thevalve body 72 has a larger diameter part 102 a and a smaller diameterpart 102 b. The outer circumferential faces of those larger diameterpart 102 a and smaller diameter part 102 b are fitted onto supportingfaces 18 a and 18 b having a circular section in the rear cover 18 withsealing members 82 and 83 therebetween, respectively, to be slidable inthe direction of the axis L.

[0055] A plurality of preload springs 85 . . . are supported by the rearcover 18 so as to surround the axis L, and the valve body 72 whosestepped part 102 c between the larger diameter part 102 a and thesmaller diameter part 102 b is pressed by these preload springs 85 . . .is urged forward to bring the sliding faces 77 of the stationary valveplate 73 and the moving valve plate 74 into close contact with eachother.

[0056] A steam feed pipe 86 connected to the rear face of the valve body72 communicates with the sliding faces 77 via a first steam passage P1formed within the valve body 72 and a second steam passage P2 formed inthe stationary valve plate 73. Among the casing body 12, the rear cover18 and the rotor 22, there is formed a steam discharge chamber 88 sealedwith a sealing member 87. The steam discharge chamber 88 communicateswith the sliding faces 77 via sixth and seventh steam passages P6 and P7formed within the valve body 72 and a fifth steam passage P5 formed inthe stationary valve plate 73. Between the mating faces of the valvebody 72 and the stationary valve plate 73 are provided with sealingmembers 89 surrounding the connecting part between the first and secondsteam passages P1 and P2 and sealing members 90 surrounding theconnecting part between the fifth and sixth steam passages P5 and P6.

[0057] Five third steam passages P3 . . . arranged at equal intervalsaround the axis L penetrate the moving valve plate 74, and both ends offive fourth steam passages P4 . . . formed in the rotor 22 so as tosurround the axis L communicate with the third steam passages P3 . . .and the expansion chambers 43 . . . , respectively. While the partsopening in the sliding faces 77 of the second steam passages P2 arecircular, those opening in the sliding faces 77 of the fifth steampassage P5 are formed in an arcuate shape centering on the axis L.

[0058] Next will be described the operation of the expander E accordingto the first embodiment configured as described above.

[0059] High temperature high pressure steam generated by heating waterin an evaporator flows from the steam feed pipe 86, and reaches thesliding face 77 of the moving valve plate 74 via the first steam passageP1 formed in the valve body 72 of the rotary valve 71 and the secondsteam passage P2 formed in the stationary valve plate 73 integral withthis valve body 72. The second steam passage P2 opening in the slidingface 77 momentarily communicates for a predetermined air intake periodwith the corresponding third steam passage P3 formed in the moving valveplate 74 turning integrally with the rotor 22. The high temperature highpressure steam is supplied from the third steam passage P3 via thefourth steam passage P4 formed in the rotor 22, into the expansionchamber 43 within the cylinder sleeve 41.

[0060] Even after the communication between the second steam passage P2and the third steam passage P3 is cut off along with the rotation of therotor 22, expansion of the expansion chamber 43 causes the piston 42fitted into the cylinder sleeve 41 to be thrust forward from the topdead center to the bottom dead center, so that the end portion 61 at thefront end of the piston presses the dimple 31 a in the swash plate 31.As a result, the reaction force which the piston 42 receives from theswash plate 31 gives a rotational torque to the rotor 22. Every time therotor 22 turns a ⅕ round, high temperature high pressure steam issupplied to a newly adjacent expansion chamber 43 to drive the rotor 22for continuous rotation.

[0061] While the piston 42 having reached the bottom dead center alongwith the rotation of the rotor 22 is pressed by the swash plate 31 torecede toward the top dead center, low temperature low pressure steamthrust out of the expansion chamber 43 is discharged, via the fourthsteam passage P4 of the rotor 22, the third steam passage P3 of themoving valve plate 74, the sliding faces 77, the arcuate fifth steampassage P5 of the stationary valve plate 73 and the sixth and seventhsteam passages P6 and P7 of the valve body 72, into the steam dischargechamber 88, and supplied therefrom to a condenser.

[0062] When the oil pump 49 provided on the output shaft 32 is actuatedalong with the rotation of the rotor 22, oil sucked from the oil pan 21via the oil pipe 52, the oil passage 95 b of the pump body 95 and theintake port 53 is discharged from the discharge port 54, and is suppliedvia the oil passage 95 c of the pump body 95, the oil passage 32 a ofthe output shaft 32, the annular groove 32 b of the output shaft 32, theoil holes 32 c . . . of the output shaft 32, the annual groove 41 b ofthe cylinder sleeves 41 and the oil holes 41 c . . . of the cylindersleeves 41 to a space between the smaller diameter part 62 b formed inthe middle portion 62 of the piston 42 and the cylinder sleeves 41. Partof the oil held in the smaller diameter part 62 b flows through thespiral oil grooves 62 d . . . formed in the middle portion 62 of thepiston 42 to lubricate the sliding face in contact with the cylindersleeve 41, and another part of the oil lubricates the sliding faces ofthe compression rings 66 and the oil rings 67 provided on the topportions 63 of the piston 42 and of the cylinder sleeve 41.

[0063] It is inevitable for water generated by the condensation of partof the supplied high temperature high pressure steam to infiltrate fromthe expansion chambers 43 onto the sliding faces of the cylinder sleeves41 and the pistons 42 to be mixed with oil. Therefore, the conditions oflubrication of the sliding faces are poor, but a sufficient oil film canbe maintained to secure the required lubricating performance bysupplying the required quantity of oil from the oil pump 49 through theinside of the output shaft 32 directly to the sliding faces of thecylinder sleeves 41 and the pistons 42. The size of the oil pump 49 canbe therefore reduced.

[0064] The oil scraped off the sliding faces of the cylinder sleeves 41and the pistons 42 by the oil ring 67 flows from the oil holes 63 c . .. formed in the bottom of the oil ring groove 63 b to the hollow spaces62 a within the pistons 42. The hollow spaces 62 a communicate with theinside of the cylinder sleeves 41 via the plurality of oil holes 62 c .. . penetrating the middle portion 62 of each piston 42, and the insideof the cylinder sleeves 41 communicates via the plurality of oil holes41 c . . . with the annual groove 41 b in the outer circumferences ofthe cylinder sleeves 41. Although the circumference of the annual groove41 b is covered by the sleeve supporting flange 34 in the middle of therotor 22, oil within the hollow spaces 62 a in the pistons 42 is urgedoutward in the radial direction by a centrifugal force, and dischargedinto the space 68 within the thermally insulating cover 40 through theoil holes 34 b in the sleeve supporting flange 34, because the oil holes34 b are formed in the sleeve supporting flange 34, and the oil is thenreturned therefrom to the oil pan 21 through the oil holes 40 a . . . inthe thermally insulating cover 40. Since the oil holes 34 b are inpositions deviating farther than the outer end of the sleeve supportingflange 34 in the radial direction toward the axis L, the oil positionedoutward from the oil holes 34 b in the radial direction is held by acentrifugal force in the hollow spaces 62 a of the pistons 42.

[0065] As described above, the oil held in the hollow spaces 62 a withinthe pistons 42 and the oil held in the smaller diameter part 62 b on theouter circumference of the pistons 42 are supplied from the smallerdiameter part 62 b toward the top portion 63 in the expansion stroke inwhich the capacities of the expansion chambers 43 increase, and they aresupplied from the smaller diameter part 62 b toward the end portion 61in the compression stroke in which the capacities of the expansionchambers 43 decrease, thereby reliably lubricating the whole area of thepistons 42 in the axial direction. Moreover, the flow of oil within thehollow space 62 a of the pistons 42 enables the heat of the top portion63 exposed to high temperature high pressure steam to be transmitted tothe low temperature end portion 61, thereby avoiding a local temperaturerise in the pistons 42.

[0066] When high temperature high pressure steam is supplied from thefourth steam passages P4 to the expansion chambers 43, the thermallyinsulating space 65 is formed between the top portion 63 and the middleportion 62 of each piston 42 facing the expansion chambers 43, and thethermally insulating space 70 is also formed in the rotor head 38 facingthe expansion chambers 43. Therefore, the escape of heat from theexpansion chambers 43 to the pistons 42 and the rotor head 38 can beminimized to contribute to improvement in the performance of theexpander E. Furthermore, as the large capacity hollow space 62 a isformed within each piston 42, not only can the weight of the piston 42be reduced but also can the thermal mass of the piston 42 be curtailedfor a more effective suppression of the escape of heat from theexpansion chambers 43.

[0067] As the metal gasket 36 is disposed between the rear sleevesupporting flange 35 and the rotor head 38 to seal the expansionchambers 43, the dead volume around the seals can be reduced as comparedwith a case in which the expansion chambers 43 are sealed by thickannular sealing members, thereby securing a large volume ratio(expansion ratio) for the expander E and enhancing the thermalefficiency to increase the output. Further, as the cylinder sleeves 41are configured as separate members from the rotor 22, the material ofthe cylinder sleeves 41 can be selected in consideration of thermalconductivity, thermal resistance, strength, wear resistance and thelike, without being restricted by the material of the rotor 22.Furthermore, only the worn or damaged cylinder sleeve 41 needs to bereplaced, resulting in an improved economy.

[0068] Moreover, because the outer circumferential faces of the cylindersleeves 41 are exposed through the two notches 57 and 58 formed in theouter circumferential face of the rotor 22 in the circumferentialdirection, not only can the weight of the rotor 22 be reduced but alsocan the thermal mass of the rotor 22 be curtailed to enhance thermalefficiency. Moreover, by causing the notches 57 and 58 to function asthermally insulating spaces, the escape of heat from the cylindersleeves 41 can be suppressed. Furthermore, as the outer circumference ofthe rotor 22 is covered with the thermally insulating cover 40, theescape of heat from the cylinder sleeves 41 can be suppressed even moreeffectively.

[0069] As the rotary valve 71 supplies and discharges steam to and fromthe group of axial piston cylinders 56 via the flat sliding faces 77between the stationary valve plate 73 and the moving valve plate 74, theleakage of steam can be effectively prevented, because the flat slidingfaces 77 can be readily machined with high accuracy and permit easiercontrol of clearances than cylindrical sliding faces do. Moreover, aspreset loads are given to the valve body 72 by the plurality of preloadsprings 85 . . . to generate surface stresses on the sliding faces 77 ofthe stationary valve plate 73 and the moving valve plate 74, steam leaksfrom the sliding faces 77 can be suppressed even more effectively.

[0070] When bringing the stationary valve plate 73 and the moving valveplate 74 into close contact with each other on their sliding faces 77while urging the valve body 72 with the preload springs 85 . . . , asthe annular member 104 supporting the valve body 72 on the rear cover 18has the pair of projections 104 a and 104 b provided at the oppositeends in the first radial direction X-X guided by the guide grooves 18 cand 18 c of the rear cover 18 to be slidable in the direction of theaxis L, the uniform frictional resistance which the pair of projections104 a and 104 b receive from the guide grooves 18 c and 18 c of the rearcover 18 prevents the annular member 104 from inclining.

[0071] Even if the pair of projections 104 a and 104 b receive unevenfriction from the guide grooves 18 c and 18 c and are inclined, as thevalve body 72 is pivotably supported on the annular member 104 via thefulcrum shaft 103 arranged in the second radial direction Y-Y, theinclination of the valve body 72 is reliably prevented. The complianceof the sliding faces 77 of the stationary valve plate 73 and the movingvalve plate 74 can be secured thereby to prevent high temperature highpressure steam from leaking and to restrain uneven wear of the slidingfaces 77.

[0072] Furthermore, as the operation of the Oldham's couplingconstructed of the annular member 104 and the fulcrum shaft 103 enablesthe annular member 104 to freely move relative to the rear cover 18 inthe first radial direction X-X and enables the valve body 72 to moverelative to the annular member 104 in the second radial direction Y-Y,the valve body 72 can freely move relative to the rear cover 18 withinthe plane orthogonal to the axis L. Therefore even if the valve body 72becomes inclined off the axis L, the free movement of the valve body 72within the plane orthogonal to the axis L prevents wrenching fromoccurring between the valve body 72 and the rear cover 18, therebyfurther enhancing the compliance of the sliding faces 77.

[0073] Further, as the valve body 72 of the rotary valve 71 is made ofstainless steel providing a larger thermal expansion amount, and thestationary valve plate 73 fixed to the valve body 72 is made of carbonor ceramic providing a smaller thermal expansion amount, there is apossibility that the centering between them is displaced due to thedifference in thermal expansion. However, as the fixed ring 79 is fixedto the valve body 72 with the plurality of bolts 80 . . . in a state inwhich the stepped portion 79 a on the inner circumference of the fixedring 79 is pressed in and spigot-fitted onto the outer circumference ofthe stationary valve plate 73 and the stepped portion 79 b on the outercircumference of the fixed ring 79 is spigot-fitted onto the outercircumference of the valve body 72, it is possible to precisely centerthe stationary valve plate 73 relative to the valve body 72 by virtue ofthe aligning effect of spigot fitting, thereby preventing the expander Efrom deteriorating in performance by keeping the supply and discharge ofsteam in time. Moreover, the contact faces of the stationary valve plate73 and the valve body 72 can be uniformly brought into close contactwith each other with the fastening force of the bolts 80 . . . , therebysuppressing steam leakage from those contact faces.

[0074] Furthermore, since the rotary valve 71 can be attached to ordetached from the casing body 12 by merely removing the rear cover 18from the casing body 12, maintenance including repairs, cleaning andreplacement can be significantly facilitated. Also, though the rotaryvalve 71 through which high temperature high pressure steam passes isincreased in temperature, oil can be prevented from being heated by thehigh temperature of the rotary valve 71 to deteriorate the lubricatingperformance of the swash plate 31 and the output shaft 32 because theswash plate 31 and the output shaft 32 which require lubrication withoil are arranged on the other side of the rotor 22 than the rotary valve71. The oil also performs the function to prevent overheating by coolingthe rotary valve 71.

[0075] When assembling the expander E, it is necessary to adjust themagnitude of the dead volume between the bottom of the cylinder sleeves41 (i.e., the lid member 69 supported by the rotor head 38) and the topof the pistons 42, namely the capacities of the expansion chambers 43when the pistons 42 are at the top dead center. If the shim 97intervening between the flange 32 d of the output shaft 32 and the innerraces of the combined angular bearings 23 f and 23 r is thinned, theoutput shaft 32 will move forward (rightward in FIG. 1), resulting in arightward shift of the rotor head 38 as well, but the dead volume willdecrease because the pistons 42 are restricted by the swash plate 31 tobe unable to move forward. Conversely, if the shim 97 is thickened, therotor head 38 will move backward (leftward in FIG. 1) together with theoutput shaft 32, and accordingly the dead volume will increase. As aresult, it is possible to adjust the dead volume as desired by merelyreplacing the shim 97, and the step otherwise needed for dead volumeadjustment can be eliminated to achieve a substantial time saving.

[0076] Further, as a single shim 97 having a predetermined thickness issandwiched between the flange 32 d of the output shaft 32 and thecombined angular bearings 23 f and 23 r, to adjust the dead volume onlyby fastening with a single nut 98 the front cover 15 incorporating theangular bearing 30 supporting the swash plate 31 and the combinedangular bearings 23 f and 23 r supporting the rotor 22 and the rotor 22incorporating the pistons 42 . . . , the adjustment procedure issimplified as compared with the conventional adjustment procedure inwhich the thicknesses of two shims, front and rear, are individuallyadjusted. Moreover, since the rotor 22 incorporating the pistons 42 . .. can be kept assembled into the casing body 12 when adjusting the deadvolume, the adjusted dead volume can be confirmed while directlywatching the state of contact between the pistons 42 . . . and the swashplate 31.

[0077] When the position of the output shaft 32 relative to the combinedangular bearings 23 f and 23 r is adjusted back and forth by varying thethickness of the shim 97, the position of the rotor head 38 at the rearend of the rotor 22 also shifts back and forth, but there is no problemin adjusting the position of the output shaft 32 because the rotor head38 is slidable in the direction of the axis L relative to the inner raceof the radial bearing 24 disposed between it and the casing body 12.

[0078] Then, when the pressure of high temperature high pressure steamsupplied to the expansion chambers 43 urges the pistons 42 in thedirection of being thrust out of the cylinder sleeves 41, the pressingforce of the pistons 42 presses forward (rightward in FIG. 1) the outerrace of the combined angular bearings 23 f and 23 r via the swash plate31, the angular bearing 30, the swash plate holder 28 and the frontcover 15, and the pressing force of the cylinder sleeves 41 reverse indirection to the suppressing force of the pistons 42 presses backward(leftward in FIG. 1) the inner race of the combined angular bearings 23f and 23 r via the rotor head 38 and the output shaft 32. Thus, the loadgenerated by the high temperature high pressure steam supplied to theexpansion chambers 43 is cancelled within the combined angular bearings23 f and 23 r, without being transmitted to the casing body 12.

[0079] While the rotor 22 constructed of the output shaft 32, the threesleeve supporting flanges 33, 34 and 35, the rotor head 38 and thethermally insulating cover 40 is made of a ferrous material whosethermal expansion is relatively small, the casing 11 which supports therotor 22 via the combined angular bearings 23 f and 23 r and the radialbearing 24 is made of an aluminum-based material whose thermal expansionis relatively large. As a consequence, there arises a difference in thequantity of thermal expansion in the direction along the axis L betweenthe high and low temperatures of the expander E.

[0080] The casing 11 which is greater in thermal expansion than therotor 22 expands more than the rotor 22 and its size in relativelyincreases in the direction of the axis L when the temperature is high.Conversely, when the temperature is low, it contracts more and its sizerelatively decreases in the direction of the axis L. As the casing 11and the rotor 22 are positioned in the direction of the axis L via thecombined angular bearings 23 f and 23 r, the difference in thermalexpansion between them is absorbed by the sliding contact of the rotorhead 38 with the inner race of the radial bearing 24, so that anexcessive load is prevented from acting in the direction of the axis Lon the combined angular bearings 23 f and 23 r, the radial bearing 24and the rotor 22. This not only contributes to an increase in thedurability of the combined angular bearings 23 f and 23 r and of theradial bearing 24, but also to stabilization in support of the rotor 22,thereby facilitating its smooth rotation. Moreover, it is possible toprevent the fluctuation in dead volume between the top of the cylindersleeves 41 and the top of the pistons 42 accompanying the change intemperature.

[0081] The reason is that, supposing that both ends of the rotor 22 arerestrained by the casing 11 to be immovable in the axial direction, asthe casing 11 tends to contract in the direction of the axis L relativeto the rotor 22 when the temperature is low, the pistons 42 whose top isin contact with the swash plate 31 supported by the swash plate holder28 which is part of the casing 11, are pressed backward, and the rotorhead 38 supported by the casing 11 via the radial bearing 24 is pressedforward, so that the pistons 42 are pressed into the cylinder sleeves 41and the dead volume decreases accordingly. Conversely, when thetemperature is high, as the casing 11 tends to extend in the directionof the axis L relative to the rotor 22, the pistons 42 are drawn outfrom the inside of the cylinder sleeves 41, resulting in an increase indead volume, which in turn invites an increase in the initial volume ofhigh temperature high pressure steam in the normal operating state afterthe warming-up, i.e. a drop in thermal efficiency due to a decrease inthe volume ratio (expansion ratio) of the expander E.

[0082] By contrast, in this embodiment of the invention, as the rotor 22is supported in a floating state in the direction of the axis L relativeto the casing 11, the gaps between the combined angular bearings 23 fand 23 r and the radial bearing 24 are prevented from widening and soare the preloads from decreasing, and the dead volume is prevent fromfluctuating due to temperature change. This enables the volume ratio(expansion ratio) of the expander E to be prevented from fluctuating,thereby achieving a stable performance.

[0083] Especially, for the expander E which uses high temperature highpressure steam as the working medium, the above-described advantage ishighly effective because the difference is wide between high temperatureand low temperature. Furthermore, although the difference between hightemperature and low temperature is particularly wide in the vicinity ofthe rotary valve 71 to which high temperature high pressure steam issupplied, the difference in thermal expansion between the casing 11 andthe rotor 22 can be absorbed without problem because the rotor head 38can be in sliding contact in the direction of the axis L with the radialbearing 24 arranged closer to the rotary valve 71.

[0084] Further, out of the stationary valve plate 73 and the movingvalve plate 74 of the rotary valve 71, as the stationary valve plate 73supported by the casing 11 is urged by the springing force of thepreload springs 85 . . . toward the moving valve plate 74 supported bythe rotor 22, the sealing performance of the sliding faces 77 of thestationary valve plate 73 and the moving valve plate 74 will not beaffected even if the positional relationship between the casing 11 andthe rotor 22 in the direction of the axis L varies along withtemperature variations. Not only that, an excessive load is preventedfrom acting on the combined angular bearings 23 f and 23 r and theradial bearing 24, resulting in stabilization of the rotational plane ofthe rotor 22 and accordingly in an improvement in the sealingperformance of the sliding faces 77, to reduce the quantity of leakedsteam.

[0085] Next will be described a second embodiment of the presentinvention with reference to FIG. 17.

[0086] In the above-described first embodiment, in order to cause theannular member 104 to be fitted onto the outer circumference of thevalve body 72, part of the valve body 72 is separated as the cap member102 and, after the annular member 104 is fitted onto the outercircumference of the valve body 72, the cap member 102 is coupled to thevalve body 72.

[0087] The second embodiment is designed to configure the valve body 72and the cap member 102 as a single member, by bisecting the annularmember 104 at the center of the projections 104 a and 104 b forassembly. The bisected projections 104 a are engaged integrally by a pin105 penetrating the pin holes 104 d and 104 d, and the bisectedprojections 104 b are engaged integrally by a pin 106 penetrating thepinholes 104 e and 104 e. As the projections 104 a and 104 b engage withthe guide grooves 18 c and 18 c of the rear cover 18, the pins 105 and106 cannot come off the pin holes 104 d, 104 d and 104 e, 104 e.

[0088] The second embodiment can also achieve operations and effectssimilar to that achieved by the first embodiment.

[0089] Although the preferred embodiments of the present invention hasbeen described above, the invention may be modified in various wayswithout deviating from the subject matter.

[0090] For example, the rotating fluid machine according to theinvention is not limited to the application to the expander E, and isalso applicable to a compressor, a hydraulic pump, a hydraulic motor andthe like.

[0091] Although the expander E in the embodiments is provided with thegroup of axial piston cylinders 56 as the working section, the structureof the working section is not limited thereto.

What is claimed is:
 1. A rotating fluid machine comprising: a casing; arotor rotatably supported by the casing; a working section disposed onthe rotor; and a rotary valve, provided between the casing and therotor, for controlling the supply and discharge of a working medium toand from the working section, the rotary valve being constructed bybringing, into contact on sliding faces which are orthogonal to an axisof the rotor, a moving valve plate provided on the rotor and astationary valve plate provided on a valve body engaged with the casingto be unable to rotate and movable in the direction of the axis, whereintwo projections are provided in a first radial direction at two ends ofan annular member loosely fitted onto the outer circumference of thevalve body, and engaged slidably in the direction of the axis with guidegrooves formed in the casing, and wherein the valve body is pivotablysupported on the annular member via a fulcrum shaft arranged in a secondradial direction orthogonal to the first radial direction.
 2. Therotating fluid machine according to claim 1, wherein the two projectionsof the annular member can slide with respect to the guide grooves of thecasing in the first radial direction, and the valve body can slide alongthe fulcrum shaft in the second radial direction.